Lower alkyl esters of fluorinated propionic acid and a method of making the esters



Patented Jan. 22, 1952 PROPIONIC ACID AND A EIETHOD OF MAKING THE ESTERS David Chaney, Nether Providence Township,

Delaware (Bounty, lPa., assignor to American.

Viscose Corporation, porationz-of Delaware Wilmington, Del., a cor- No Drawing. Original application June 28, 1946,

Serial 680,055.

Divided and this application June 4; 1948; Serial No. 31,204

This" invention relates to" alkyl' esters of fluorinated propionic acids of the formula in which X is selected from the group consisting of fluorine and chlorine, and R isan alkyl group containing from lto' 4.carbons.

The present application is a division. of my pending application, Serial'No. 680,055, filed June 28, 1946, now Patent No. 2,456,768.

The 'nevwfluorinated esters" are obtainedby reaction of' the selected alcohol with fluorinated propionyl" chlorides or"fluorides obtained by the oxidation of correspondingly fiuorinated'propyh enes. The propylenes are oxidized by passing a streamoi oxygen, preferably mixed with at least a small'iamount of chlorine gas which serves as a catalyst for thetreaction, into a vessel containingthe fiuorinatedpropylene and equippedwith suitable stirring means anda source of internal actinic radiation, such as a mercury vapor lamp.

encasedin a quartz tube extending into the vessel. The gas is passed in until the acyl halideis formed, as indicated by a marked decrease in the gas absorption rate, and .var-ying from 50 hours to about.120 hours depending upon the propylene being oxidizedand other conditions such as the efiic'iency ofstirring,the concentration ofch'lorine and the intensity of the radiation.

The temperature at'which the oxidation is conducted. may. vary, somewhat, depending :upon the boiling point of the-propylene being oxidized and the solubilities of'the gases therein, which decrease with increasing temperature, but is preferably maintained within the range of from about 30""to 80C., the reaction vesselbeing externally cooled to dissipate the heat of the a'ctinic'radia tion source The reaction of oxygen with the propylene of the type .under consideration apparently results in'the formation of an intermediate oxide ot-the general formula where X "has the same significance as above, which by rearrangement involving a shift of 'a halogen atom from one carbon to another, is converted to the corresponding acyl halide. Most unexpectedly, this shift of a halogen atom and rearrangement to form the acid halide takes place, in the case of the propylenes under consideration, not only with respect to chlorine, but under the conditions described herein, with respect to the perhalogenated methyl group. Thus,

e Claims. (01. 260-487) when 1,1,3 ---trichloro 2,3,3 -trifiuoropropene 1 (CF2ClCF=CCl2) is oxidized, the oxidafionprod uct comprises both the acid chloride (CFzClCFClCOCl) mer due to a shift of a chlorine atom, the latter due to a shift of CFzCl, the rearrangement taking place according to the following scheme:

First step.oxidation-.

O enemi -ooh OFQCICFCCI;

Second step-rearrangement-= (1) Shift-of chlorine:

A .1 orzoloroo z OFZCIGFGIGOOI.

(2) Shift of substituted methyl group:

oin olcr ooh orzowolzoor v Theoxidaormixture of oxides present inthe reaction product may. be converted to the acyl chloride or. mixture of acyl chloride and acyl fluoride by treatment with an amine such as pyridineor, in the case Ofnon-fluorine containing compounds, by treatment with FriedelE-Craits typesalts,

The'fluorinated esters,.which are useful as =in-- termediates invarious chemical processes, as solvents,.etc., may-be produced by. treating the oxidationproduct of the propylene comprising the acyl halide with the alcohol without isolation of the halide, .or the acyl halidemay be isolated 4i the alcohol.

The following examplesin which thepartsareand the acid fluoride (CF2C1CC12COF) the. forfrom the oxidation productandsthen reacted with CF2C1CC12COC1 and an oxide believed to be The acid chloride was converted to the ethyl ester by adding the reaction mixture to about 1600 parts of absolute alcohol, with'cooling and stirring, the temperature being maintained at about 30 C. The mixture was allowed to stand for.

about one hour and then poured into 4,000 parts of water. The products which separated as an oil were washed with dilute sodium bicarbonate, then with water, and after drying over sodium sulfate, were fractionally distilled. About 1,670 parts of the ethyl ester of a-dichloro-fi-difluorochloropropionic acid were obtained, B. P. 170- 174 C., N =1.425.

Example II In an apparatus as described in Example I, 4730 parts of 1,1,3-trich1oro-2,3,3-trifluoropropene-l (CF2ClCF=CCl2) 'were photo-oxidized as described in Example I to a mixture consisting primarily of a-chlorofiuoro-p difluorochloropropionyl chloride (CFzClCFCICOCl), a-dichloro 6-difluorochloropropionyl fluoride and an oxide believed to be CFZCICFCCh o The reaction mixture also comprised some unoxidized 7 starting material, some chlorinated product, and by-products "resulting from more complete oxidation and degradation, including C0012, CO, and CFzClCOCl. The temperature during the reaction was maintained at about 35 C; The 10 to 1 mixture of gaseous oxygen and chlorine gas was absorbed at the rate of 300 mL/min. When the absorption rate dropped to about 50 ml./min, which required about 30 hours, the reaction was terminated.

The contents of the flask were then slowly heated to about 50 C. to remove dissolved chlorine gas and low-boiling by-products.

The acid halides were converted to the corresponding acid esters in the manner described in Example I, that is by adding the crude reaction liquid to absolute ethanol. After fractional distillation, the pure esters were obtained. The

4 tained by reacting the propionyl halide with the appropriate alcohol, such as methanol, butanol, propanol, etc

I claim: 1. An ester of a fiuorinated propionic acid of the general formula CFzXCClXCOOR V where X is selected from the group consisting of fluorine and chlorine, and R is an alkyl radical containing from 1 to 4 carbons.

2. The ethyl ester of alpha,alpha-dichlorobeta,beta-difluorometa-chloropropionic acid.

3. The ethyl ester of alpha-chloro,alphafluoro-beta,beta-difluoro beta chloropropionic acid.

4. Method of making esters of fiuorinated propionic acids having the general formula propionic acid had a boiling point of 142 C., re-

fractive index N 1.3830, and (1 1.405. The ethyl ester of a-dichloro-fl-difluorochloropropionic acid had a boiling point of about 172.5 C., refractive index N 1.4188 and d 1.460.

Instead of ethyl esters, other esters may be ob- CFzXCClXCOOR where X is selected from the group consisting of fluorine and chlorine, and R is an alkyl radical containing from 1 to 4 carbons, which comprisesv treating a fiuorinated propylene of formula with oxygen mixed with chlorine gas, under the influence of actinicradiation and reacting the acyl halide thus obtained with a lower aliphatic alcohol.

g 5. .Method of producing the ethyl ester of alpha,alphadichloro beta,beta difluoro betachloropropionic acid which comprises treating a. fiuorinated propylene of formula CF2C1CC1=CC12 with oxygen mixed with chlorine gas, under the influence of actinic radiation and reacting'the acyl chloride thus obtained with ethanol.

6. Method of producing a mixture comprising the ethyl ester of alphachloro,alpharfiuorqbeta,beta-difluoro beta chloropropionic acid which comprises treating a fluorinated propylene of the formula CF2C1CF=CC12 I with oxygen mixed with chlorine gas, under'the influence of-actinic radiation to produce a mixture of acid halides of the formulae j CFzClCF'ClCOCl' and CFzClCClzCOF and reacting the mixed halides with ethanol.

DAVID W. CHANEY,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Fieser et al.: Organic Chemistry,

(D. C. Heath; Boston; 1944), pp. 186-187. 

4. METHOD OF MAKING ESTERS OF FLUORINATED PROPIONIC ACIDS HAVING THE GENERAL FORMULA 